FEATHERED GIANTS 127 



only a few hundred pounds so that his big relation 

 might almost swallow him at a gulp. And Diatryma 

 in spite of its size has naught to do with ostriches though 

 its real relationships are, as is often the case, so obscured 

 by specialization that its real affinities are doubtful, 

 the more that some of the parts that would throw most 

 light upon the problem are crushed and distorted. 



Thus in some ways Diatryma is an aggravation; it 

 gives us no help in understanding the inter-relation- 

 ships of birds, but offers an additional puzzle to be 

 solved: we can only say that it is one of the largest of 

 the true birds, those provided with a fan-shaped tail. 

 At any rate it is the earliest known giant bird and 

 another bit of evidence of the rapidity with which birds 

 developed once they were fairly started on their career. 



Something, perhaps, remains to be said concerning 

 the causes which seem to have led to the development of 

 these giant birds, as well as the reasons for their flight- 

 less condition and peculiar distribution, for it will be 

 noticed that, with the exception of the African and 

 South American ostriches the great flightless birds as a 

 rule are, and were, confined to uninhabited or sparsely 

 populated islands, and this is equally true of the many 

 small, but equally flightless birds. It is a seemingly 

 harsh law of nature that all living beings shall live in a 

 more or less active struggle with each other and with 

 their surroundings, and that those creatures which 

 possess some slight advantage over their fellows in the 

 matter of speed, or strength, or ability to adapt them- 

 selves to surrounding conditions, shall prosper at the 

 expense of the others. In the power of flight, birds 

 have a great safeguard against changes of climate with 

 their accompanying variations in the supply of food, 

 and, to a lesser extent, against their various enemies, 

 including man. This power of flight, acquired early in 



